The present invention relates to a disc brake assembly of the movable caliper type, and more particularly to a disc brake assembly of the movable caliper type which comprises a pair of parallel guide pins fixed to a stationary torque member, a movable caliper member having a pair of support arms, each arm being axially slidable on a corresponding one of the guide pins, and a pair of tubular sealing boots for each support arm, the boots of each pair having inner ends attached to opposite sides of the corresponding of the support arms and having outer ends attached to the corresponding one of the guide pins in such a way as to enclose a pair of annular openings formed between the support arm and the guide pin at opposite outer and inner sides of the support arm.
In a conventional disc brake assembly of this kind, the tubular sealing boots are provided to prevent entry of water, dirt, dust and the like into the annular openings between the guide pin and the support arm so as to ensure smooth operation of the disc brake assembly. For example, as is illustrated in FIG. 5, a guide pin 3 fixed to a torque member is provided at opposite outer and inner end portions with a pair of annular grooves 3a, 3b, and respectively and a pair of tubular sealing boots 1 and 2 are fixedly coupled at their outer sealing ends 1a, 2a within the annular grooves 3a, 3b of guide pin 3. Although in such attachment of the tubular sealing boots 1, 2, the respective outer sealing ends 1a, 2a are engaged within the annular grooves 3a, 3b with a predetermined press fit, the outer sealing end 1a of boot 1 is apt to be upturned and removed by a jet of water acting thereon during car washing under high pressure. This results in entry of water, dirt, dust and the like into the interior of boot 1, causing an obstacle in operation of the brake assembly.